Enhancement of teletex procedures to incorporate encipherment and signatures

A method of applying U.S. Data Encryption Standard encipherment to Teletex is described. The possibility of encipherment at the session level, the mode of encipherment, and the extent of the cryptographic chain are considered. The establishment of a new key and initialization variable for each session is recommended, and three alternative methods for key distribution are described. The sequence of events in a successful session, including enciphered documents, is given. Other considerations are encipherment parameters and signature procedures.